1. Field of the Invention
The invention relates to an angiography catheter comprising a hose-like body with at least one lumen debouching in an end opening at the distal end. The distal end has a permanent curvature and a number of openings is arranged in the wall of the catheter.
2. Description of the Related Art Including Information Disclosed Under 37 CFR .sctn.1.97-1.99
Such a catheter is, for example, a diagnostic cardiac catheter which is guided via a blood vessel into the heart. A contrast liquid can be introduced via the lumen so that the contours of, for example, a ventricle of the heart of a patient can be made visible on an X-ray screen in a catheter laboratory. In accordance with the area of the blood vessel system of the patient to be examined, a catheter is used with a specific curvature, which curvature is designed such that the distal end of the catheter will assume a stable position in the intended area.
With known angiography catheters of this type, the curvature can deform quite considerably during injection of the contrast liquid as a result of the reaction forces of the contrast liquid flowing in the curvature and spurting outward from the end opening. This can endanger the stable position of the end portion of the catheter.
The invention now has for its object to improve a catheter of the type described in the preamble such that it also has a stable position during injection of the contrast liquid.
This objective is achieved with an angiography catheter, as characterized in claim 1. Due to the openings arranged in the curvature in a side of the wall remote from the end opening, a quantity of liquid is discharged and the reaction forces resulting from the remaining liquid become accordingly smaller. The pressure in the curvature is thereby also lower whereby the "uncurling", as a result of a Bourdon spring effect, is likewise reduced. Moreover, a reaction force is herein generated which attempts to bend the catheter in a direction opposite to that in which the catheter is bent by the reaction force of the liquid coming out of the end opening. These effects largely cancel each other out so that during injection of the contrast liquid, even if this takes place at high pressure a very limited deformation, at most, of the permanent curvature of the catheter occurs. The angiographic examination can hereby take place more rapidly and accurately.
The invention can be applied particularly well with an angiography catheter of the so-called "pigtail" type. The curvature herein is a circular curvature through practically 360.degree.. In the known "pigtail" catheter, the curvature is bent outward by the reaction force of the liquid spurting out from the end opening, whereby the desired shape of the curvature is disturbed and the direction in which the contrast liquid spurts out is moreover considerably altered. With the catheter according to the invention of the type, openings are arranged in the first 180.degree. of the curvature in the outward facing portion of the wall. These openings drain off a portion of the liquid, whereby the forces in and on the curvature become smaller because the quantity of liquid and the pressure thereof in the curvature decrease. The liquid flowing outward through the openings causes a reaction force which results in strengthening of the curvature of the catheter and, thus, counteracts the "uncurling".
The placing of the openings in the manner according to the invention moreover has the advantage that contrast liquid is better directed towards the apex of the heart ventricle under examination, so that the whole action of the catheter is improved.
The openings arranged in the curvature are preferably additional to the usual openings in the portion of the basic body lying in advance of the curvature. The number of openings in the catheter, according to the invention, is thus larger than in a catheter according to the prior art, so that a more uniform egress of contrast liquid over a larger area is achieved. This moreover achieves that the total quantity of liquid coming out of the end opening is smaller and the pressure of the jet coming out of he end opening of the wall of the heart ventricle toward which this jet is directed during the examination, can decrease greatly. Heart arrhythmia occurring with catheters of this type, according to the prior art, are hereby avoided.